Galileo’s championing of heliocentrism and Copernicanism was controversial during his lifetime, when most subscribed to either geocentrism or the Tychonic system. Three of Galileo’s five siblings survived infancy. Michelangelo was unable to contribute his fair share of their father’s promised dowries to their brothers-in-law, who would later attempt to seek legal remedies for payments due. When Galileo Galilei was eight, his family moved to Florence, but he was left with Jacopo Borghini for two years. He then was educated in the Vallombrosa Abbey, about 30 km southeast of Florence. Galilei in his honor in the late 14th century.

It was common for mid-sixteenth century Tuscan families to name the eldest son after the parents’ surname. Hence, Galileo Galilei was not necessarily named after his ancestor Galileo Bonaiuti. The biblical roots of Galileo’s name and surname were to become the subject of a famous pun. Ye men of Galilee, why stand ye gazing up into heaven?

She is buried with him in his tomb in the Basilica of Santa Croce, Florence. Despite being a genuinely pious Roman Catholic, Galileo fathered three children out of wedlock with Marina Gamba. Because of their illegitimate birth, their father considered the girls unmarriageable, if not posing problems of prohibitively expensive support or dowries, which would have been similar to Galileo’s previous extensive financial problems with two of his sisters. Their only worthy alternative was the religious life. Although Galileo seriously considered the priesthood as a young man, at his father’s urging he instead enrolled at the University of Pisa for a medical degree. In 1589, he was appointed to the chair of mathematics in Pisa.

In 1591, his father died, and he was entrusted with the care of his younger brother Michelagnolo. In 1592, he moved to the University of Padua where he taught geometry, mechanics, and astronomy until 1610. Cardinal Bellarmine had written in 1615 that the Copernican system could not be defended without “a true physical demonstration that the sun does not circle the earth but the earth circles the sun”. For Galileo, the tides were caused by the sloshing back and forth of water in the seas as a point on the Earth’s surface sped up and slowed down because of the Earth’s rotation on its axis and revolution around the Sun.

He circulated his first account of the tides in 1616, addressed to Cardinal Orsini. If this theory were correct, there would be only one high tide per day. Galileo and his contemporaries were aware of this inadequacy because there are two daily high tides at Venice instead of one, about twelve hours apart. Galileo dismissed this anomaly as the result of several secondary causes including the shape of the sea, its depth, and other factors.

In 1619, Galileo became embroiled in a controversy with Father Orazio Grassi, professor of mathematics at the Jesuit Collegio Romano. Because The Assayer contains such a wealth of Galileo’s ideas on how science should be practised, it has been referred to as his scientific manifesto. The Assayer was Galileo’s devastating reply to the Astronomical Balance. It has been widely recognized as a masterpiece of polemical literature, in which “Sarsi’s” arguments are subjected to withering scorn. Galileo’s dispute with Grassi permanently alienated many of the Jesuits who had previously been sympathetic to his ideas, and Galileo and his friends were convinced that these Jesuits were responsible for bringing about his later condemnation. Opposition to heliocentrism and Galileo’s writings combined religious and scientific objections and were fueled by political events.